Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752792AbaAPQoe (ORCPT ); Thu, 16 Jan 2014 11:44:34 -0500 Received: from qmta06.emeryville.ca.mail.comcast.net ([76.96.30.56]:56783 "EHLO qmta06.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752673AbaAPQo2 (ORCPT ); Thu, 16 Jan 2014 11:44:28 -0500 Date: Thu, 16 Jan 2014 10:44:24 -0600 (CST) From: Christoph Lameter X-X-Sender: cl@nuc To: Dave Hansen cc: Joonsoo Kim , Pekka Enberg , Andrew Morton , "linux-mm@kvack.org" , LKML Subject: Re: [PATCH 0/9] re-shrink 'struct page' when SLUB is on. In-Reply-To: <52D5B48D.30006@sr71.net> Message-ID: References: <20140103180147.6566F7C1@viggo.jf.intel.com> <20140103141816.20ef2a24c8adffae040e53dc@linux-foundation.org> <20140106043237.GE696@lge.com> <52D05D90.3060809@sr71.net> <20140110153913.844e84755256afd271371493@linux-foundation.org> <52D0854F.5060102@sr71.net> <20140113014408.GA25900@lge.com> <52D41F52.5020805@sr71.net> <52D5B48D.30006@sr71.net> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 14 Jan 2014, Dave Hansen wrote: > On 01/14/2014 12:07 PM, Christoph Lameter wrote: > > One easy way to shrink struct page is to simply remove the feature. The > > patchset looked a bit complicated and does many other things. > > Sure. There's a clear path if you only care about 'struct page' size, > or if you only care about making the slub fast path as fast as possible. > We've got three variables, though: > > 1. slub fast path speed The fast path does use this_cpu_cmpxchg_double which is something different from a cmpxchg_double and its not used on struct page. > Arranged in three basic choices: > > 1. Big 'struct page', fast, medium complexity code > 2. Small 'struct page', slow, lowest complexity The numbers that I see seem to indicate that a big struct page means slow. > The question is what we should do by _default_, and what we should be > recommending for our customers via the distros. Are you saying that you > think we should completely rule out even having option 1 in mainline? If option 1 is slower than option 2 then we do not need it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/